| 2024 | Friends of the Sea Lions Inc | 990 | Secretary | 0.25 | $0 | $0 | View return |
| 2024 | Halvorsen Family Foundation | 990PF | Trustee | 0.3 | $0 | $0 | View return |
| 2024 | Halvorsen Family Foundation | 990PF | Trustee | 0.3 | $0 | $0 | View return |
| 2024 | The Rockefeller University | 990 | Trustee | 2 | $0 | $0 | View return |
| 2023 | United States Ski Team Foundation | 990 | Trustee | 1 | $0 | $0 | View return |
| 2023 | Friends of the Sea Lions Inc | 990 | Secretary | 2 | $0 | $0 | View return |
| 2023 | The Rockefeller University | 990 | Trustee | 2 | $0 | $0 | View return |
| 2022 | Friends of the Sea Lions Inc | 990 | Secretary | 2 | $0 | $0 | View return |
| 2022 | Halvorsen Family Foundation | 990PF | Trustee | 0.3 | $0 | $0 | View return |
| 2021 | Darien Community Association Inc. | 990 | Director | 2 | $0 | $0 | View return |
| 2021 | Lincoln Elementary School PTA | 990 | Recording Sec | 20 | $0 | $0 | View return |
| 2021 | Friends of the Sea Lions Inc | 990 | Board Member | 2 | $0 | $0 | View return |
| 2021 | Sterling and Francine Clark Art Institute | 990 | Trustee | 1 | $0 | $0 | View return |
| 2021 | Halvorsen Family Foundation | 990PF | Trustee | 0.3 | $0 | $0 | View return |
| 2020 | New England Nordic Ski Association | 990 | Director | 2 | $0 | $0 | View return |
| 2020 | Friends of the Sea Lions Inc | 990 | Board Member | 2 | $0 | $0 | View return |
| 2020 | Darien Community Association Inc. | 990 | Director | 2 | $0 | $0 | View return |
| 2020 | Halvorsen Family Foundation | 990PF | Trustee | 0.3 | $0 | $0 | View return |
| 2020 | Sterling and Francine Clark Art Institute | 990 | Trustee | 1 | $0 | $0 | View return |
| 2019 | Darien Community Association Inc. | 990 | Director | 2 | $0 | $0 | View return |
| 2019 | New England Nordic Ski Association | 990 | Director | 2 | $0 | $0 | View return |
| 2019 | Friends of the Sea Lions Inc | 990 | Board Member | 2 | $0 | $0 | View return |
| 2019 | Lincoln Elementary School PTA | 990 | Treasurer | 20 | $0 | $0 | View return |
| 2019 | Halvorsen Family Foundation | 990PF | Trustee | 0.3 | $0 | $0 | View return |
| 2019 | Sterling and Francine Clark Art Institute | 990 | Trustee | 1 | $0 | $0 | View return |
| 2018 | Darien Community Association Inc. | 990 | Director | 2 | $0 | $0 | View return |
| 2018 | Lincoln Elementary School PTA | 990 | Treasurer | 20 | $0 | $0 | View return |
| 2018 | New England Nordic Ski Association | 990 | Director | 2 | $0 | $0 | View return |
| 2018 | Halvorsen Family Foundation | 990PF | Trustee | 0.3 | $0 | $0 | View return |
| 2018 | Sterling and Francine Clark Art Institute | 990 | Trustee | 1 | $0 | $0 | View return |
| 2017 | Lincoln Elementary School PTA | 990 | Secretary | 20 | $0 | $0 | View return |
| 2017 | Teachers College Columbia University | 990 | Trustee | 1 | $0 | $0 | View return |
| 2017 | Halvorsen Family Foundation | 990PF | Trustee | 0.3 | $0 | $0 | View return |
| 2017 | Darien Community Association Inc. | 990 | Director | 2 | $0 | $0 | View return |
| 2016 | New England Nordic Ski Association | 990 | Director | 2 | $0 | $0 | View return |
| 2016 | Lincoln Elementary School PTA | 990 | President | 20 | $0 | $0 | View return |
| 2016 | Sterling and Francine Clark Art Institute | 990 | Trustee | 1 | $0 | $0 | View return |
| 2016 | Teachers College Columbia University | 990 | Trustee | 1 | $0 | $0 | View return |
| 2016 | Halvorsen Family Foundation | 990PF | Trustee | 0.3 | $0 | $0 | View return |
| 2015 | New England Nordic Ski Association | 990 | Director | 2 | $0 | $0 | View return |
| 2015 | Sterling and Francine Clark Art Institute | 990 | Trustee | 1 | $0 | $0 | View return |
| 2015 | Teachers College Columbia University | 990 | Trustee | 1 | $0 | $0 | View return |
| 2015 | Halvorsen Family Foundation | 990PF | Trustee | 0.3 | $0 | $0 | View return |
| 2014 | New England Nordic Ski Association | 990 | Director | 2 | $0 | $0 | View return |
| 2014 | Sterling and Francine Clark Art Institute | 990 | Trustee | 1 | $0 | $0 | View return |
| 2013 | New England Nordic Ski Association | 990 | Director | 2 | $0 | $0 | View return |
| 2013 | Sterling and Francine Clark Art Institute | 990 | Trustee | 1 | $0 | $0 | View return |
| 2010 | Halvorsen Family Foundation | 990PF | Trustee | 0.3 | $0 | $0 | View return |